L7 · Add, subtract, and multiply multi-digit decimals

1. 1.

   Find 6.54 + 2.21.

   Answer. 8.75

   Add hundredths: 654 + 221 = 875 hundredths → 8.75.

2. 2.

   Find 7.46 − 2.13.

   Answer. 5.33

   746 − 213 = 533 hundredths → 5.33.

3. 3.

   Find 6.7 × 4.3.

   Answer. 28.81

   6.7 × 4.3 = 28.81.

4. 4.

   Find 2.82 + 2.16.

   Answer. 4.98

   Add hundredths: 282 + 216 = 498 hundredths → 4.98.

5. 5.

   Find 7.38 − 2.11. Then Nora needs 4 of that amount. What is the total they need?

   Answer. 21.08

   738 − 211 = 527 hundredths → 5.27. Then multiply by 4: 21.08.

6. 6.

   Find 6.4 × 3.8. Then Owen needs 4 of that amount. What is the total they need?

   Answer. 97.28

   6.4 × 3.8 = 24.32. Then multiply by 4: 97.28.

7. 7.

   Find 6.96 + 0.77. Then Sam needs 4 of that amount. What is the total they need?

   Answer. 30.92

   Add hundredths: 696 + 77 = 773 hundredths → 7.73. Then multiply by 4: 30.92.

8. 8.

   Find 5.63 − 2.11. Then Grace needs 2 of that amount. What is the total they need?

   Answer. 7.04

   563 − 211 = 352 hundredths → 3.52. Then multiply by 2: 7.04.

9. 9.

   Find 7.4 × 3. Then Owen needs 5 of that amount. What is the total they need?

   Answer. 111

   7.4 × 3 = 22.2. Then multiply by 5: 111.

10. 10.

    Find 3.82 + 1.15. Then Nora needs 5 of that amount. What is the total they need?

    Answer. 24.85

    Add hundredths: 382 + 115 = 497 hundredths → 4.97. Then multiply by 5: 24.85.

11. 11.

    Think

    Malik tried this problem:
    Find 6.23 − 0.93.
    Malik wrote 4.3. That is not correct. What is the right answer?

    Answer. 5.3

    Malik’s answer 4.3 is off. 623 − 93 = 530 hundredths → 5.3.

12. 12.

    Think

    Sam tried this problem:
    Find 5.9 × 2.9.
    Sam wrote 16.11. That is not correct. What is the right answer?

    Answer. 17.11

    Sam’s answer 16.11 is off. 5.9 × 2.9 = 17.11.

Original extra practice. Keys are computed from the items, not guessed.